Bancroftian Filariasis Infection Research Articles

Current Epidemiological Assessment of Bancroftian Filariasis in Tanga Region, Northeastern Tanzania.

Background. Tanzania started a countrywide lymphatic filariasis elimination programme in 2000 adopting the mass drug administration (MDA) strategy. The drug used for the programme was the combination of ivermectin and albendazole. However, there is limited information on the current epidemiological trend of the infections, where MDA implementation is ongoing. The present study aimed at assessing the current status of Bancroftian filariasis infection rate and morbidity where MDA has been distributed and administered for over eight rounds. Methodology. The study was a cross-sectional descriptive study involving 272 individuals (>18 years) from endemic communities in Tanga region where MDA has been implemented. Clinical, sociodemographic, and circulating filarial antigen (CFA) test was undertaken using immune chromatographic card test according to the manufacturer's instructions. Results. A total of 472 individuals were screened: 307/472 (65.1%) were males while 165/472 (34.9%) were females. The overall prevalence of CFA was 5.51%, that of hydrocoele was 73.2%, and that of lymphoedema was 16.0%. The prevalence of hydrocoele combined with lymphoedema was 5.5%. Conclusion. Our findings demonstrate a considerable reduction in filarial infection. However, there is clear evidence of ongoing transmission despite the 8 rounds of MDA. It is unlikely that the annual MDA would interrupt filarial transmission; therefore, additional strategies are needed to accelerate lymphatic filariasis control and elimination.

Survey of Bancroftian filariasis infection in humans and Culex mosquitoes in the western Brazilian Amazon region: implications for transmission and control

The aim of this work was to identify possible lymphatic filariasis foci in the western Brazilian Amazonian that could be established from the reports of Rachou in the 1950s. The study was conducted in three cities of the western Brazilian Amazon region - Porto Velho and Guajará-Mirim (State of Rondônia) and Humaitá (State of Amazonas). For human infection evaluation thick blood smear stained with Giemsa was used to analyze samples collected from 10pm to 1am. Polymerase chain reaction (PCR) was used to examine mosquito vectors for the presence of Wuchereria bancrofti DNA. Humans were randomly sampled from night schools students and from inhabitants in neighborhoods lacking sanitation. Mosquitoes were collected from residences only. A total 2,709 night students enrolled in the Program for Education of Young Adults (EJA), and 935 people registered in the residences near the schools were examined, being 641 from Porto Velho, 214 from Guajará-Mirim and 80 from Humaitá. No individual examined was positive for the presence of microfilariae in the blood stream. A total of 7,860 female Culex quinquefasciatus specimens examined were negative by PCR. This survey including human and mosquito examinations indicates that the western Amazon region of Brazil is not a focus of Bancroftian filariasis infection or transmission. Therefore, there is no need to be included in the Brazilian lymphatic filariasis control program.

Aspectos da realidade social de crianças e adolescentes atendidos em serviço de referência para filariose bancroftiana, Recife, estado de Pernambuco

The authors report on aspects of the social realities of children and adolescents living in Jaboatão dos Guararapes, State of Pernambuco, who were diagnosed with Bancroftian filariasis infection and were treated at the Filariasis Teaching, Research and Care Center of the Federal University of Pernambuco (Health Sciences Center), which is a tertiary-level reference service for filariasis. The patients' housing conditions were quantified and classified as subhuman, with a direct relationship with the maintenance of Bancroftian filariasis transmission, and the authors highlight the need for political decisions regarding the implementation of basic sanitation projects.

Sensitivity of the Immunochromatographic Card Test Relative to Detection of Adult Wuchereria bancrofti Worms by Ultrasound

The diagnosis of active infection in bancroftian filariasis continues to pose an important and continuously evolving challenge to filariasis-endemic countries and to health personnel. Sensitivity of the immunochromatographic card test (ICT) relative to detection of adult Wuchereria bancrofti worms by ultrasound was evaluated in a retrospective study conducted in the Center for Teaching, Research and Tertiary Referral Hospital for bancroftian filariasis (Federal University of Pernambuco) in Recife, Brazil. The results showed that among 408 persons tested, the overall sensitivity of the ICT was 84.5% and varied from 52% to 100% when patients were grouped by different criteria (age, sex, presence or absence of living adult worms by ultrasound, microfilaremia status/density). The present study provides evidence that a negative antigen result should be interpreted cautiously and may help to explain the different sensitivities of the antigen test found by different investigators in settings with different transmission intensities.

Treatment of co-infection with bancroftian filariasis and onchocerciasis: a safety and efficacy study of albendazole with ivermectin compared to treatment of single infection with bancroftian filariasis

BackgroundIn order to use a combination of ivermectin and albendazole for the elimination of lymphatic filariasis, it is important to assess the potential risk of increased adverse events in individuals infected with both lymphatic filariasis and onchocerciasis. We compared the safety and efficacy of albendazole (400 mg) in combination with ivermectin (150 micrograms/kg), for the treatment of co-infections of Wuchereria bancrofti and Onchocerca volvulus with single infection of W. bancrofti.MethodsThe safety study on co-infections was a crossover, double blind design, while for the single infection of bancroftian filariasis an open design comparing two treatments was used. For co-infection, one group was allocated a single dose of ivermectin (150 micrograms/kg) plus albendazole (400 mg) (Group A). The other group received placebo (Group B). Five days later the treatment regime was reversed, with the Group A receiving placebo and Group B receiving treatment. For the single bancroftian filariasis infection, one group received a single dose of albendazole (400 mg) plus ivermectin (150 μg/kg) (Group C) while the other group received a single dose of albendazole (400 mg) alone (Group D). Blood and skin specimens were collected on admission day, day 0, and on days 2, 3, and 7 to assess drug safety and efficacy. Thereafter, blood and skin specimens were collected during the 12 months follow up for the assessment of drug efficacy. Study individuals were clinically monitored every six hours during the first 48 hours following treatment, and routine clinical examinations were performed during the hospitalisation period and follow-up.ResultsIn individuals co-infected with bancroftian filariasis and onchocerciasis, treatment with ivermectin and albendazole was safe and tolerable. Physiological indices showed no differences between groups with co-infection (W. bancrofti and O. volvulus) or single infection (W. bancrofti). The frequency of adverse events in co-infected individuals was 63% (5/8, Group A, albendazole + ivermectin) and 57% (4/7, Group B, placebo) and of mild or moderate intensity. In single W. bancrofti infection the frequency of adverse events was 50% (6/12, Group C, albendazole + ivermectin) and 38% (5/13, Group D, albendazole) and of a similar intensity to those experienced with co-infection. There were no differences in adverse events between treatment groups. There was no significant difference in the reduction of microfilaraemia following treatment with albendazole and ivermectin in groups with single or co-infection.ConclusionOur findings suggest that ivermectin plus albendazole is a safe and tolerable treatment for co-infection of bancroftian filariasis and onchocerciasis.

Bancroftian filariasis infection, disease, and specific antibody response patterns in a high and a low endemicity community in East Africa.

Bancroftian filariasis infection, disease and specific antibody response patterns in a high and a low endemicity community in East Africa were analyzed and compared to assess the relationship between these parameters and community transmission intensity. Overall prevalences of microfilaremia and circulating filarial antigenemia were 24.9% and 52.2% in the high and 2.7% and 16.5% in the low endemicity community, respectively. A positive history of acute attacks of adenolymphangitis was given by 12.2% and 7.1% of the populations, 4.0% and 0.9% of the adult (> or = 20 years old) individuals presented with limb lymphedema, and 25.3% and 5.3% of the adult males had hydrocele, in the high and the low endemicity community, respectively. Both infection and disease appeared earlier and reached much higher levels in the high than in the low endemicity community. The observed overall and age-specific infection and disease patterns in the two communities were in agreement with the view that these are primarily shaped by transmission intensity. No statistically significant relationships between infection status of fathers and mothers and that of their children were observed in any of the communities for either microfilaremia or for circulating filarial antigenemia. The overall levels (prevalence and geometric mean intensity) of filarial-specific IgG1, IgG2, IgG4, and IgE were significantly higher in the high endemicity community than in the low endemicity dommunity. Surprisingly, the opposite pattern was found for IgG3. Community transmission intensity thus appears to be an important determinant of observed inter-community variation in infection, disease, and host response patterns in Bancroftian filariasis.

Evaluation of PCR-based methods for the diagnosis of infection in bancroftian filariasis

The value of the polymerase chain reaction (PCR) in the diagnosis of Wuchereria bancrofti infection was evaluated in comparison to microscopical examination of night blood smears, Nuclepore ® filtration, serology and ultrasonography. No correlation was found between PCR-based deoxyribonucleic acid (DNA) probing and serology. We did not find any evidence of free filarial DNA in either blood plasma or chylocoele fluid. We conclude that the 2 PCR-based techniques evaluated are not more sensitive than Nuclepore ® filtration for detection of W. bancrofti microfilaraemia, need at least 1 intact microfilaria in the volume of blood used for DNA extraction, and were much inferior to ultrasonography for detection of amicrofilaraemic adult worm carriers.

Impact of single-dose ivermectin on community microfilaria load in bancroftian filariasis infection: two years post treatment

The concept of annual single-dose treatment for the control and possible interruption of transmission of lymphatic filariasis has brought much hope to the previously hopeless disease. The logistics for implementing this enormous public health intervention have wide ramifications and will depend on the efficiency of drug delivery and distribution at various levels of the health system. In sub-Saharan Africa, where the public health services are inadequate, this becomes even more important. Six communities in southern Ghana known to be endemic for filariasis were treated with single-dose ivermectin in January/ February 1997 as part of pilot programme activities. The 1998 treatment could not take place because of unavailability of the drug. The 1999 community microfilaraemia prevalence and intensity were reduced by only 25·5% and 39·5% of pre-treatment levels, respectively. The implications of any shortfalls on the drug delivery system on the goal of elimination of lymphatic filariasis are discussed.

Risk factors for the occurrence of bancroftian filariasis infection in children living in endemic areas of northeast of Brazil.

The objective of this study was to identify biological and social risk factors for the occurrence of microfilaraemia in a population of 1464 children of both sexes aged 5-14 years, living in two highly endemic areas of Recife a city in the northeast of Brazil. A survey was performed from December 1990 to July 1991 and the microfilaraemia was examined by the thick-drop technique using 45 microliters of peripheral blood. Information was obtained about use of bednet, length of time living in area and number of occupants per household. Risk was quantified by the crude and adjusted Odds Ratio. The 95 per cent confidence interval, Likelihood Ratio Statistics, and P value were used to test the statistical significance. An association was established between microfilaraemia in children and adolescents, and age, number of individuals per household, the presence of microfilaraemic adults in the household, length of time living in the area, and bednet use. Maternal microfilaraemia was not found to be a risk factor for the occurrence of microfilaraemia in offspring. These results allow the identification of children with a greater risk of microfilaraemia. In addition, these findings highlight the role of the household environment in the transmission process.

Detection of filarial antigen by inhibition enzyme linked immunosorbent assay using fractionatedBrugia malayi microfilarial excretory secretory antigen

Detection of filarial antigen in blood or urine samples would provide an accurate indication of active infection. The absence of a simple, well established animal model and limitations in getting the required amount of parasite material from human sources have been the main obstacles for the diagnosis ofWuchereria bancrofti infection. An inhibition ELISA has been developed for detection of filarial antigen using a partially purifiedBrugia malayi mf ES antigen (BmE DE1) and its affinity purified antibodies. Filarial antigen was detected in the sera of 88% of microfilaraemic, 60% of chronic filarial, 17% of endemic normal and none of the non- endemic normal subjects. The sensitivity and specificity of the assay were 88% and 89% respectively. Moreover, undiluted urine samples from 82% of microfilaraemic and 17% of endemic normal, but none of the non- endemic normal samples showed the presence of filarial antigen. With the limitations on the availability of sufficient homologous parasite materials, the inhibition ELISA using BmE DE1 and anti BmE DE1 antibodies shows promise for the detection of active infection in bancroftian filariasis in man. Moreover, its detection in urine makes it more possible to test patients in field areas.